A Method Of Aligning A Pattern On A Workpiece
a workpiece and pattern technology, applied in the direction of circuit inspection/indentification, instruments, printed circuit aspects, etc., can solve the problems of large tooling capital investment, not yet in commercial use, and the pattern of holes to be distorted from the initial design pattern
Inactive Publication Date: 2007-01-04
IBM CORP
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Benefits of technology
The invention is a method for aligning patterns in a set of layers so that they are vertically adjacent and have corresponding features within a tolerance. This allows for a minimum overlap between adjacent layers. The method involves defining a pattern on a layer and measuring a subset of pattern features in each layer. The best fit locations of a second set of fiducial marks are then computed to maintain the pattern features within a tolerance value of their ideal locations. The second set of fiducial reference marks is then formed at the best fit locations.
Problems solved by technology
It is known that the punching process and other causes cause the pattern of holes to be distorted from the initially designed pattern.
This approach is not yet in commercial use and has some practical problems to overcome.
This approach would require a large capital investment for tooling.
Method used
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[0014]FIG. 1 shows a plan view of a workpiece 10, such as a ceramic greensheet, having a pattern 100 comprising four blocks 110 formed in it. In the example of a greensheet, the preferred method of defining a pattern is by mechanically punching apertures through the material of the greensheet. In the case of a mask for a stepper in integrated circuit fabrication, a wafer for fabricating integrated circuits or printed circuit boards, the method of defining a pattern may be by projecting an alignment mark onto a photosensitive material, then developing the photo-material and etching the underlying substrate to form the marks.
[0015] A first set of marks 10-1 through 10-4 represent a first set of fiducial reference marks, in this case represented schematically by circles. The first set of fiducials will be formed within a set of nominal reference mark spaces. The pattern 100 has been distorted to represent the effect of various causes of distortion such as mechanical stress on the gree...
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Abstract
A first set of fiducials is formed in fiducial locations on a workpiece such as a ceramic greensheet; a pattern is formed in the workpiece; a best fit set of fiducials is formed by a least squares technique based on the pattern; and a second set of fiducials is formed over the fiducial locations of the best fit set.
Description
TECHNICAL FIELD [0001] The field of the invention is that of aligning a pattern projected on a workpiece with respect to reference marks, in particular aligning a set of punched apertures on a ceramic greensheet. BACKGROUND OF THE INVENTION [0002] In the course of manufacturing a ceramic integrated circuit holder, a set of ceramic greensheets are formed with a pattern, usually by punching holes placed relative to a set of fiducial reference marks. The set of greensheets is aligned in a stack and fired to form a block in which the pattern of holes in the various layers line up to form conductive vias that will carry signals vertically between different layers. [0003] It is known that the punching process and other causes cause the pattern of holes to be distorted from the initially designed pattern. [0004] One approach that is known in the art is to use laser drilling rather than mechanical punching of the vias. This approach is not yet in commercial use and has some practical proble...
Claims
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IPC IPC(8): G06K9/00
CPCH05K1/0269H05K1/0306H05K3/4629H05K2203/166H05K2201/09063H05K2201/09918H05K2203/1476H05K3/4638
Inventor ANDERSON, RHONDA M.HUMENIK, JAMES N.KATZ, ROBERT P.KELLNER, BENEDIKT M.O'NEIL, KEITH C.WERNER, RANDALL J.
Owner IBM CORP